Trust is referred to as the confidence level individuals possess towards a particular event, other individuals, machinery/equipment, or specific situations, as well as individuals believing that all decisions/actions adopted are perceived as being fair, unbiased, impartial and socially acceptable.

Human Factors Benefits of Trust

1) The greater the existence of trust level, the greater the level of effectiveness of utilising automation to execute performance (as one does not doubt the performance capability of automation in assisting in daily works). For instance, pilots have to trust their flight computers, autopilots and the performance of all technologies (avionics/aerodynamics) of the entire aircraft. Likewise, Air Traffic Controllers (ATC) need to trust their radar and communication equipments.

Comprehending trust

1) Due to more automated and computerised support, trust has become an important aspect of daily operations.

2) Trust is difficult to gain but easy to lose. It is even more difficult to gain lost trust back.

3) Trust should neither be at an inadequate nor excessive level. Individuals must still be able to recognise that they may be under-trusting (When system is highly reliable yet trust is low) or over-trusting (when system reliability is low yet trust is high), in order to execute the correct amount of trust or distrust.

4) As distrust is more difficult to change than trust, it is essential to assure of high system reliability prior to wide usage.

5) It is essential to know that the difference between trust and self-confidence. Trust is related to the system characteristics (e.g reliability, effectiveness, efficiency) while self-confidence is related to individual personal performance (e.g. accident rate, success rate).

Development of Trust

1) Early testings of a new equipment system should involve its future users, in order to study the system fitting and limitations effectively for reliability.

2) Subsequent improvisations should be based on testing users’ criticism and compliments.

3) The sample size of testing users should be large enough to be accurately representative in studying system fit and limitations for its future users.

4) Since distrust is a more challenging perspective to change than trust, developers must ensure of high system reliability even in its early stage of introduction. This will allow trust to build up sufficiently prior to wide usage.

5) Users must be trained sufficiently to get used to the functions and pattern of usage. However, user training should not be used to offset undesirable system design. Users may be trained using Computer-Based Training (CBT) at own pace, realistic simulation and auditors-monitored performance assessment under all probable scenairos.

6) It is important to study users’ level of trust towards a particular system, using survey questionnaires.

7) Other than system glitches, it is necessary to highlight possible human errors and subsequent strategies to avoid them.

8) Avoid causing psychological stress to introduce new systems without adequate testings.

Preparations for Loss of Trust

1) Anticipation of system failures and implementation of backups (system, equipment, human resources) can support possible early system loopholes and allow normal operations. For instance, the Boeing 747 features backups in the forms of structural reinforcements, additional hydraulic systems, four sets of main landing gear and double control systems.

1. Eurocontrol. (2003, May 5). Guidelines for Trust in Future ATM Systems: Principles. Retrieved 10 September 2010, from
2. Skybrary. (2009). Trust. Retrieved 10 September 2010, from
3. Sutter, J. (2006). 747: Creating the world's first jumbo jet and other adventures from a life in aviation. Washington, DC: Smithsonian Books.

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